How to test java application for performance bottlenecks?

Question

I am reviewing a big java application to see if there are any performance bottlenecks. The real problem is that I cannot pinpoint the performance issues to any single module. The whole application is slow as such.

Is there some tool/technique I can use to help me out in this?

Answer 1

Try using a profiler on your running code. It should help you identify the bottlenecks. Try jprofiler or Netbeans profiler

Answer 2

If you are running on Java 6 you can use the supplied monitoring tools

Answer 3

You could have a look at this post too: http://stackoverflow.com/questions/12927/if-you-have-a-java-application-that-is-consuming-cpu-when-it-isnt-doing-anythin

Answer 4

For testing/development purposes, you can download Oracle JRockit Mission Control for free from this site. (Requires Login, but accounts can be set up with any email adress)

Docs Here. It will allow you to find hotspots, memory leaks and much more.

Answer 5

I'm often happy enough using Java -Xprof. This gives you a sorted list of the functions your code spends most of its time in.